Hey guys, Well we got some Ice/snow tonight so i had to pop my truck into 4x4, Everything was fine until i got close to home, from a dead stop i heard a clunk, thought maybe i ran over a chunk of ice, later while making a turn it clunked again, Then finally Clunked one more time on my way home while accelerating, 2 times it was from a dead stop going straight, The other time was while driving and turning into a parking lot, I dont believe it clunked at all last year when i used it in 4x4, It NEVER clunks while the 4x4 is off, It took me about 2 hours to get home so it only made the noise 3 times within that amount of time but all happend in the last 20minutes of my drive, Is this normal for it to clunk from time to time? My tranny couldnt be bad since it never clunks in 2 wheel drive could it? Thanks!

 

I would suspect that the front axle in not fully locking into place. A vacuum leak in the system may cause it to not fully lock and it will clunk under stress.
Check the vacuum lines from the solenoids on the firewall to the vacuum motor on the front differential. There are reservoirs behind the battery that can also leak.

JMC

 

Also, not sure if you have vacume hubs, but I had to repack my hubs to take care of clunk and grinding noises. Also, make sure your ball joints are good and your springs haven't snapped.